... regularly.Possible reasons of malfunction and solutions of unit:Possible Malfunctions: 1,Battery exhausted. (Solutions:Change to specialized battery) 2, ... Circuit, PCB contactor or other contactor poorly connected. (Solutions:Inject lubricant, screw down the ring on the Head and ... or disconnection of head, body or tail cap switch. (Solutions:Inject lubricant, screw down the ring on the Head and ...